Divide pastry in half and roll out one half to line a 18 cm/7" shallow pie plate. Put to chill whilst you prepare the apples.
Peel, core and thickly slice the apples, toss with the grated rind from the whole lemon and juice from half, flour, sugar and cinnamon. Pile into the pastry base.
Roll out remaining pastry and use to top the pie, using trimmings for decoration as desired - we cut out rounds of pastry with a small cutter and then add stalks to give an ‘apple' motif. Brush with water and sprinkle lightly with remaining sugar, bake for 20-25 mins until pastry is golden brown.
Serve warm with cream, custard or ice cream.